What's Up Doc? Fifth disease is contagious - but not from Fido

My daughter had that slapped cheek disease this past winter. My neighbor said it was from parvovirus, and that she probably caught it from our dog because dogs get parvovirus. Is this right?

Dr. Jeff Hersh

Q: My daughter had that slapped cheek disease this past winter. My neighbor said it was from parvovirus, and that she probably caught it from our dog because dogs get parvovirus. Is this right?

A: Parvovirus is one of the most common viral illnesses in dogs - most common in puppies - and can give them diarrhea (often bloody) and vomiting. It is often a serious illness and can cause severe dehydration or, in some cases, can affect other organs such as the dog's heart. It is too often fatal.

You should speak with your veterinarian to learn more about this disease; there are vaccinations for dogs to prevent this illness. However, the strains of parvovirus dogs get do not infect people.

Parvovirus B19 is the concerning strain of parvovirus that does affect people. It was discovered in 1975 during screening tests for hepatitis on donated blood, and was found to be associated with disease in people in 1981.

The childhood illness from parvovirus B19, erythema infectiosum, is often called fifth disease. This comes from an early 1900s list of childhood illnesses that cause a rash, and included measles, scarlet fever (from strep infection), rubella (German measles), staph skin infection (or possibly a different form of scarlet fever), erythema infectiosum and roseola.

Since erythema infectiosum was fifth on this list, it was sometimes called fifth disease. Although the list number did not "stick" as a common name for the other illnesses, it did for fifth disease.

Fifth disease is a very common childhood illness. In fact, 30 percent to 60 percent of adults have antibodies to it, showing that they had the disease or at least were exposed to it.

The classic symptoms of childhood fifth disease are "flu-like" symptoms including runny nose, low-grade fever, cough and not feeling well. Some kids who get fifth disease develop a classic rash of rosy red cheeks that look like they were slapped in the face (usually both sides), so fifth disease is sometimes also called slapped cheek disease. The rash may spread to the arms and legs. For the overwhelming majority of kids, this is a mild, self-limited illness.

Since many people infected with parvovirus B19 have very mild symptoms or no symptoms at all, most people do not recall having had this disease. However, for some people there can be complications of parvovirus B19 infection, and these can sometimes be severe.

Some adults infected with parvovirus B19 get more than just a flu-like illness. Inflammation of the joints (arthritis), the heart (myocarditis) or other organ involvement can occur. Pregnant women who become infected can pass the infection on to their fetus.

Sometimes this can cause the fetus to stop producing red blood cells and they may develop hydrops fetalis, a condition where fluids seep into their body tissues and cavities because of the very low levels of blood keeping the fluids inside their blood vessels. This condition can sometimes lead to fetal death.

People with certain red blood cell disorders, such as sickle cell disease, hereditary spherocytosis or thalassemia who are infected with parvovirus B19 can have an aplastic crisis, where the bone marrow stops producing blood cells. This can be severe and cause complications, often requiring transfusions and other treatments.

Parvovirus B19 is very contagious. It is spread like many other viruses, from the mucous and sputum of infected patients who sneeze and cough. It is estimated that more than 50 percent of susceptible household contacts of an infected person will also become infected.

So, although getting parvovirus from your dog is not a concern, getting it from another infected person is.

There is no available vaccine to prevent parvovirus B19 infection in humans. For those people who are at a higher risk of having complications from this disease, such as pregnant women or people with certain red blood disorders, the key to prevention is to minimize contact with someone who is infected.

This can be tricky because infected people are actually most contagious when they have the non-specific, flu-like symptoms, before the characteristic rash appears (if it is going to appear), so it is best to minimize contact with anyone with a flu-like illness.